Survival International said it has not received a response from the letter it sent Finsbury or WPP's head Martin Sorrell, the agency's parent company.

The NGO claims that mining company Vedanta is planning to mine bauxite from an Indian mountain which will destroy the lives of the 8,000 members of the Dongria Kondh tribe that live in the surrounding Niyamgiri Hills.

The British company rejects the allegations saying it is committed to socially responsible business.